KR20050089322A - Sn-al lead-free solder alloy composition and method to prepare the sn-al lead-free solder alloy - Google Patents

Abstract

The present invention discloses a tin-aluminum lead-free solder alloy composition, wherein the lead-free solder alloy composition is composed of 0.1 to 2 wt% aluminum and 98 to 99.9 wt% tin. In addition, the present invention, the step of providing a first material containing tin ions, a second material containing aluminum ions, or a mixture of the first material and the second material (S1); And at least one additive material selected from the group consisting of LiClO ₄ , LiH, LiAlH ₄ , PSA, ENSA, and POELE, adding the first material and the second material, or adding the mixture. And, by performing the electroplating, to provide a tin-aluminum alloy (S2); discloses a method for producing a tin-aluminum lead-free solder alloy comprising a. The tin-aluminum lead-free solder alloy provided according to the tin-aluminum lead-free solder alloy composition of the present invention and the manufacturing method of the tin-aluminum lead-free solder alloy is not found in the known lead-free solder alloy, and is a conventional flexible Compared with solder, it has better properties in electrical conductivity, etc., and has a relatively low melting point, good ductility, good electrical and thermal conductivity, good coefficient of thermal expansion, good wettability, and other good mechanical properties such as lead-free solder alloy. . Furthermore, aluminum used in the production of tin-aluminum lead-free solder alloys has various advantages that are compatible with solder, such that it is rich in quantity, easy to obtain, can be purchased at a relatively low price, and is harmless to the human body. Thus, the tin-aluminum lead-free solder alloy according to the present invention achieves the effect of sufficiently replacing the existing flexible solder.

Description

Sn-Al lead-free solder alloy composition and method to prepare the Sn-Al lead-free solder alloy}

The present invention relates to a tin-aluminum lead-free solder alloy composition and a method for producing a tin-aluminum lead-free solder alloy, specifically, a novel tin-aluminum lead-free solder alloy that can replace conventional leaded solder and lead-free solder alloy compositions. A composition and method for producing a tin-aluminum lead-free solder alloy.

Tin-lead solders have long been used as the most effective bonding material for electronic devices.

However, when disposing of the electronic device to which the flexible solder is applied, the lead component contained in the solder is eluted by acid rain, which contaminates the groundwater, and when it is absorbed by the human body, serious damage to the human body, such as reduced intelligence and reduced reproduction, is caused. There was a problem.

Accordingly, a review of lead regulation in solders for electronic devices was conducted in the United States in 1990. As a result, research on lead-free solder alloy compositions has been conducted worldwide.

The research related to the development of Pb-free solder alloy compositions first proceeded to the NCMS project (1992-1996) in the United States, to the IDEALS project (1996-1999) in Europe, and to the basics and application of Pb-free solder alloy compositions in Japan. It is estimated to be ahead of Europe and the US in terms of technology.

For the development of lead-free solder alloy compositions, there is a need for a successful replacement of lead, which requires an understanding of the role of lead in tin-lead solder.

The role of lead in solders can be understood by investigating the effect on the physical properties of the alloy with tin, which leads to lower solder melting points when applied to solder and increases the content of lead in tin-lead solders. The electrical and thermal conductivity decreases while the coefficient of thermal expansion increases.

In addition, as the lead content increases, the viscosity of the tin-lead solder decreases, but the surface tension is lower than that of pure tin, which means an improvement in the wettability of the solder.

As such, lead has a very important influence on material properties such as melting point, electrical and thermal conductivity, thermal expansion coefficient, flowability, surface tension, mechanical properties, etc. in the solder and, therefore, in the development of current solders, it is a substitute for lead. However, it is required to have better or equivalent properties than the material properties of conventional tin-lead solders.

Therefore, the lead-free solder alloy composition should have the following characteristics.

First, lead-free solder alloy compositions should have a low melting point similar to tin-lead solder.

Second, the lead-free solder alloy composition should have the same or better physical properties as the tin-lead solder. In other words, good electrical and thermal conductivity, good coefficient of thermal expansion, good wettability, etc. are required.

Third, lead-free solder alloy compositions should have good mechanical properties, often characterized by shear strength and tensile strength.

Fourth, lead-free solder alloy compositions should have improved shelf life and tissue stability.

Fifth, the lead-free solder alloy composition should have improved or equivalent degree of corrosion resistance and ductility than tin-lead solder.

Finally, the lead-free solder alloy composition should be non-toxic and present in large quantities to provide sufficient supply, and the material should be of a lead level low price.

In order to meet such demands, many studies have been conducted on lead-free solder alloy compositions. Examples of representative binary solders include tin-copper (Sn-Cu) solders, tin-silver (Sn-Ag) solders, Tin-bismuth (Sn-Bi) -based solders, tin-zinc (Sn-Zn) -based solders, and the like, to date, are known to be powerful as replacement solders.

However, the conventional lead-free solder alloy compositions all have their disadvantages, and have a level equivalent to that of tin-lead (Sn-Pb) solder, which does not completely replace the existing flexible solder.

Therefore, there is a need for a new lead-free solder alloy composition that differs from materials conventionally known as lead-free solder.

Accordingly, the present invention has been made to solve the above problems and needs,

The object of the present invention is that the lead-free solder has better electrical conductivity than the conventional solder, and has a relatively low melting point, good ductility, good electrical and thermal conductivity, good coefficient of thermal expansion, good wettability, and other excellent mechanical properties. To provide a lead-free solder alloy composition and a lead-free solder alloy having the physical properties required for the alloy composition.

The object of the present invention as described above is achieved by a tin-aluminum lead-free solder alloy composition, which is composed of 0.1 to 2 wt% aluminum and 98 to 99.9 wt% tin in the lead-free solder alloy composition.

The object of the present invention as described above also comprises the steps of providing a first material comprising tin ions, a second material comprising aluminum ions, or a mixture of the first material and the second material (S1); And at least one additive material selected from the group consisting of LiClO ₄ , LiH, LiAlH ₄ , PSA, ENSA, and POELE, adding the first material and the second material, or adding the mixture. And, by performing an electroplating, to provide a tin-aluminum alloy (S2); is achieved by the method for producing a tin-aluminum lead-free solder alloy comprising a.

And, the step S1, the first material containing the tin ions, SnCl ₂ , SnCl ₄ , SnBr ₂ , SnBr ₄ , SnI ₂ , SnSO ₄ , SnS, SnO ₂ , SnF ₂ and Sn (BF ₄ ) ₂ It is preferable to use at least one selected from the group consisting of, and as the second material containing the aluminum ion, AlCl ₃ , AlBr ₃ , Al (OH) ₃ , Al ₂ O ₃ , Al ₄ C ₃ , Al Preference is given to using at least one substance selected from the group consisting of ₂ (SO ₄ ) ₃ , Al ₂ S ₃ , AlI ₃ and AlNH ₄ (SO ₄ ) ₂ .

In the S2 step, it is preferable to use an ether solvent, an aromatic hydrocarbons solvent, or a dimethylsulfone solvent as the organic solvent.

Hereinafter, the tin-aluminum lead-free solder alloy composition and the manufacturing method of the tin-aluminum lead-free solder alloy according to the present invention will be described in detail.

First, in the present invention, in the lead-free solder alloy composition, aluminum is selected as a material for replacing lead, which has high thermal and electrical conductivity, high corrosion resistance in the atmosphere, small specific gravity, and easy processing in various forms. In addition, since the amount is rich and harmless to the human body, it is sufficient to replace the lead in the conventional solder.

Specifically, the tin-aluminum lead-free solder alloy composition of the present invention is composed of tin and aluminum, wherein the mass ratio of the tin and the aluminum alloy composition is 0.1 to 2% aluminum and 98 to 99.9 in mass percentage. It is preferable that it is% of tin, and plating surface characteristics, physical characteristics, etc. fall in the range other than the said range.

In order to manufacture the tin-aluminum lead-free solder alloy using the tin-aluminum lead-free solder alloy composition, first, a first material containing tin ions, a second material containing aluminum ions, or a mixture thereof is prepared. To provide (S1).

The first material may be used alone or in combination of SnCl ₂ , SnCl ₄ , SnBr ₂ , SnBr ₄ , SnI ₂ , SnSO ₄ , SnS, SnO ₂ , SnF ₂ , or Sn (BF ₄ ) ₂ .

The second material is AlCl ₃ , AlBr ₃ , Al (OH) ₃ , Al ₂ O ₃ , Al ₄ C ₃ , Al ₂ (SO ₄ ) ₃ , Al ₂ S ₃ , AlI ₃ , AlNH ₄ (SO ₄ ) ₂ can be used individually or in mixture.

Then, for example, the first material and the second material, or the mixture is added to a solution in which an additive material of LiClO ₄ is dissolved in a THF (Tetrahydrofuran) organic solvent, and electroplating through an electrochemical reaction Performing to obtain a tin-aluminum alloy (S2).

That is, in a solution in which a first material containing tin ions, a second material containing aluminum ions, and LiClO ₄ are dissolved in THF, the reduction potentials of the tin and aluminum are confirmed, and the electropotential experiment is performed at the reduction potential of aluminum. An electroplated tin-aluminum alloy is obtained.

The additive material may be used to inhibit or activate the reaction of the first material and the second material. In addition to the LiClO ₄ , a material such as LiH, LiAlH ₄ , PSA, ENSA, POELE, or the like may be used.

As the organic solvent, an ether organic solvent, an aromatic hydrocarbon organic solvent, a dimethyl sulfone organic solvent, or the like is used. For example, as described above, a THF organic solvent is used.

Hereinafter, the present invention will be described in more detail by explaining preferred embodiments of the present invention. However, the present invention is not limited to the specific embodiments, only the following examples are intended to facilitate the implementation of the invention to those skilled in the art while at the same time making the disclosure of the present invention complete, the attached patent It will be understood by those skilled in the art that various forms of modifications are possible within the scope of the claims.

EXAMPLE

In Examples 1 to 4 below, the same solution conditions as those shown in Example 1, and the conditions for adding SnCl ₂ powder and AlCl ₃ powder are applied.

Example 1

In the solution in which 0.5 M of LiClO ₄ powder was dissolved in THF solvent, 0.05 M of SnCl ₂ powder and 0.05 M of AlCl ₃ were dissolved, respectively, and the reduction polarization curve behavior of each of tin and aluminum was confirmed.

In addition, 0.05 M of SnCl ₂ powder and 0.05 M of AlCl ₃ powder were dissolved together in a solution in which 0.5 M of LiClO ₄ powder was dissolved in a THF solvent to confirm the reduction polarization curve behavior of tin-aluminum.

Since the materials are very sensitive to air and moisture, all electrochemical experiments were carried out in a glove box in an argon gas atmosphere, and the temperature in the glove box was kept at 25 ° C.

1 is a graph showing the reduction polarization curve behavior of each of the above, Figure 1a is a graph showing the reduction polarization curve behavior of aluminum, Figure 1b is a graph showing the reduction polarization curve behavior of tin, Figure 1c of the tin-aluminum alloy It is a graph showing the reduction polarization curve behavior.

As can be seen in Figures 1a and 1b, the reduction potential of tin and aluminum is -300 mV, -900 mV, respectively, it can be seen that the reduction rate of tin is very fast compared to the reduction rate of aluminum.

1C and 1B show a very similar form, so that the reduction of tin is very dominant over the reduction of aluminum, and the amount of tin in the tin-aluminum alloy is much higher than that of aluminum. In addition, the mass ratio at this time is substantially consistent with the process composition of a tin-aluminum state diagram.

Example 2

Figure 2 shows the characteristics of the plating surface obtained through the electropotential experiment at -300 mV, -900 mV, and -900 mV under each solution condition of Figure 1, Figure 2a is a pure tin plated surface, Figure 2b is Plated pure aluminum surface, and FIG. 2C is a SEI photograph showing the surface of the plated tin-aluminum alloy.

As can be seen in FIG. 2A, the plated pure tin surface is very coarse and irregular in its plating surface, and as can be seen in FIG. 2B, the plated pure aluminum surface is fine but somewhat fine in its plating surface compared to FIG. 2A. Rough surface characteristics are shown.

On the other hand, as can be seen in FIG. 2C, the plated tin-aluminum alloy exhibits very dense and smooth surface properties of its plating surface. Therefore, it could be confirmed that the electroplated tin-aluminum alloy has excellent plating characteristics.

Example 3

Low melting points are essential for use in lead-free solder alloy compositions.

3 is a graph showing the melting point of the electroplated tin-aluminum alloy of this example, measured using the DSC method.

In the case of the electroplated tin-aluminum alloy, there is no effect of pure tin, so as can be seen in FIG. 3, the electroplated tin-aluminum alloy is completely solid solution. At this time, the melting point represents 228 ° C., which is a very good characteristic of the solder material.

Considering this together with the tin-aluminum composition ratio presented in this example, it can be seen that the results agree very well with the state of tin-aluminum process.

Therefore, the solution conditions and the like in this embodiment have sufficient practical possibility in carrying out the electroplating of the tin-aluminum alloy.

Example 4

4 is a graph comparing the hardness of the electroplated tin-aluminum alloy of the present embodiment with other electroplated relatively soft metals and alloys.

As can be seen in Figure 4, since the hardness of the electroplated tin-aluminum alloy shows a value of 7 ~ 10 HV it can be seen that it is a very soft metal.

In addition, the electrical conductivity of the electroplated tin-aluminum alloy was measured and averaged several times by the 4-point probe method, and the average value was 9.0 Ω ^-1 · cm ^-1, and the other lead-free solder alloy composition or tin-lead was obtained. The solder showed better electrical conductivity than (6.9 Ω ^-1 · cm ^-1 ).

As such, the tin-aluminum alloy obtained through electroplating has physical properties such as relatively low melting point, good electrical conductivity and good ductility.

In addition to the above physical properties, aluminum is also abundant in production, relatively inexpensive, and non-toxic, which is very superior to materials known to be available in conventional lead-free solder alloy compositions.

The tin-aluminum lead-free solder alloy provided according to the tin-aluminum lead-free solder alloy composition of the present invention and the manufacturing method of the tin-aluminum lead-free solder alloy is not found in the known lead-free solder alloy, and is a conventional flexible Compared with solder, it has better properties in electrical conductivity, etc., and has a relatively low melting point, good ductility, good electrical and thermal conductivity, good coefficient of thermal expansion, good wettability, and other good mechanical properties such as lead-free solder alloy. .

Furthermore, aluminum used in the production of tin-aluminum lead-free solder alloys has various advantages that are compatible with solder, such that it is rich in quantity, easy to obtain, can be purchased at a relatively low price, and is harmless to the human body.

Thus, the tin-aluminum lead-free solder alloy according to the present invention achieves the effect of sufficiently replacing the existing flexible solder.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

Figure 1a is a graph showing the reduction polarization curve behavior of aluminum in solution conditions according to an embodiment of the present invention,

Figure 1b is a graph showing the reduction polarization curve behavior of tin in solution conditions according to an embodiment of the present invention,

Figure 1c is a graph showing the reduction polarization curve behavior of the tin-aluminum alloy in solution conditions according to an embodiment of the present invention,

Figure 2a is a SEI photograph showing the plated pure tin surface obtained through the potentiostatic experiment in solution conditions in accordance with an embodiment of the present invention,

Figure 2b is a SEI photograph showing the plated pure aluminum surface obtained through the potentiometric experiments in solution conditions according to an embodiment of the present invention,

Figure 2c is a SEI photograph showing the surface of the plated tin-aluminum alloy obtained through the electropotential experiment in solution conditions according to an embodiment of the present invention,

Figure 3 is a DSC graph showing the melting point of the tin-aluminum alloy prepared according to the embodiment of the present invention,

Figure 4 is a graph showing the hardness measurement results of the tin-aluminum alloy prepared according to an embodiment of the present invention in comparison with other metals and alloys.

Claims (5)

In the lead-free solder alloy composition, A tin-aluminum lead-free solder alloy composition comprising 0.1 to 2 wt% aluminum and 98 to 99.9 wt% tin. Providing a first material comprising tin ions, a second material comprising aluminum ions, or a mixture of the first material and the second material (S1); And Into the organic solvent comprising at least one additive selected from the group consisting of LiClO ₄ , LiH, LiAlH ₄ , PSA, ENSA and POELE, the first material and the second material, or the mixture The electroplating step of providing a tin-aluminum alloy (S2); manufacturing method of a tin-aluminum lead-free solder alloy comprising a. The method of claim 2, wherein the step S1, As the first material including the tin ions, at least one selected from the group consisting of SnCl ₂ , SnCl ₄ , SnBr ₂ , SnBr ₄ , SnI ₂ , SnSO ₄ , SnS, SnO ₂ , SnF _2, and Sn (BF ₄ ) ₂ A process for producing a tin-aluminum lead-free solder alloy characterized by using one or more. The method of claim 2, wherein the step S1, As the second material including the aluminum ion, AlCl ₃ , AlBr ₃ , Al (OH) ₃ , Al ₂ O ₃ , Al ₄ C ₃ , Al ₂ (SO ₄ ) ₃ , Al ₂ S ₃ , AlI ₃ and AlNH ₄ (SO ₄ ) _{2 A} method for producing a tin-aluminum lead-free solder alloy, characterized in that at least one selected from the group consisting of: The method of claim 2, wherein the step S2, An ether solvent, an aromatic hydrocarbon solvent, or a dimethyl sulfone solvent is used as the organic solvent.